KR0150694B1 - Biodegradable resin composition - Google Patents

Abstract

The present invention relates to a biodegradable resin composition which is completely decomposed by microorganisms in the soil after use and does not cause environmental pollution, that is, 90 to 20% by weight of ethylene-vinyl alcohol having 20 to 50% ethylene and aliphatic 99 to 1% by weight of synthetic thermoplastic resin containing 10 to 80% by weight of polyester and 1 to 99% by weight of starch, the plasticizer adds 1-5% by weight of the total composition, and the lubricant adds 0.5-10% by weight. It relates to a biodegradable resin composition characterized in that. In this case, the aliphatic polyester has an intrinsic viscosity of 1.0 to 1 mol% of an acid component composed of 70 to 95 mol% of succinic acid residues and 5 to 30 mol% of adipic acid residues, 1,4-butanediol, and a compound having polyfunctionality. It is characterized by the above. The resin thus prepared can be used in various applications such as injection molded articles, sheet vacuum molded articles, blown films and T-DIE films.

Description

Degradable Resin Composition

The present invention relates to a biodegradable resin composition that is completely decomposed by microorganisms in the soil after use, and does not cause environmental pollution. More specifically, the ethylene-vinyl alcohol copolymer 90 having an ethylene content of 20 to 50% It consists of 99 ~ 1% by weight of synthetic resin and 1 ~ 99% by weight of starch composed of ~ 20% by weight and 10 ~ 80% by weight of aliphatic polyester copolymer. It relates to a biodegradable resin composition characterized in that it is melted and kneaded after adding 0.5 to 10% by weight.

In general, synthetic resin, a petrochemical product, is widely used in all fields because of its excellent physical properties such as chemical resistance, transparency, flexibility and rigidity, but it does not decompose itself after use, and environmental pollution caused by waste plastic is a big problem. As a result, research on degradable resins is being actively conducted, and has attracted much attention all over the world. In particular, as the limits of landfill use and the difficulty of recycling become more difficult, various aspects of research and development have been conducted to alleviate the problem of plastic waste disposal. have.

Generally, degradable resins are classified into biodegradable resins decomposed by microorganisms present in soil and light decomposed by ultraviolet rays of sunlight, but photodegradable resins do not receive light when they are buried in the soil. Biodegradable resin is mainly used because it has. As biodegradable resins, general-purpose resins such as polyhydroxyarylate resins synthesized in vivo by microorganisms, polycaprolactones which are synthetic polymer biodegradable resins, and thermoplastic resins polyethylene, polystyrene, polypropylene, polyethylene terephthalate, etc. Resin filled with a natural polymer material in order to impart biodegradability to the is known.

In addition, polyhydroxyarylene resin, polycaprolactone, and the like have excellent degradability but are expensive due to high manufacturing cost, and resins containing natural polymers have a problem in that required physical properties are lowered. That is, the natural polymer itself has excellent degradability, but the thermoplastic resin itself is a decomposable resin that does not decompose and partially forms a piece of the resin, causing secondary environmental pollution.

Degradable resins using starch as a natural polymer are known as EP 032,802, USP 4,900,361, EP 326,517, EP 032,802, EP 327,505, WP 90/10671, and the like. Although it was prepared in the form of a thermoplastic mixture by destroying, a satisfactory effect could not be obtained.

Biodegradable polymeric resins made from starch and ethylene-vinyl alcohol copolymers are also disclosed in EP 0400,532, which is known to have excellent mechanical properties and water resistance. However, the resin has a problem that the mechanical properties are lowered according to the change in humidity, in particular, in the low humidity has a large odor and the impact strength has been limited to use in the field of packaging products.

Accordingly, an object of the present invention is to provide a method for producing a biodegradable resin that is economical because it is completely decomposed by microorganisms in the soil after use, and does not cause environmental pollution.

In order to achieve the above object as well as another easily expressed object, the present invention uses an aliphatic polyester copolymer having starch as a natural polymer and excellent compatibility with starch as a resin and having high melt viscosity and melt strength. In order to improve the fluidity, the ethylene-vinyl alcohol copolymer having hydrophilic and hydrophobic groups was used as part of the synthetic resin to improve mechanical properties and processability, thereby obtaining biodegradable resins satisfying various properties.

The present invention will be described in more detail as follows.

Biodegradable resin of the present invention is a synthetic resin composed of 90 to 20% by weight of ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 50% and 10 to 80% by weight of aliphatic polyester copolymer and starch 99 to 1 It is obtained by adding 10 to 50% of water to starch as a main component by weight%, and adding 0.5 to 10% by weight of lubricant to the total resin composition as a resin plasticizer, and then melting and kneading by breaking starch particles at high temperature and high pressure. .

In the present invention, starch is a starch extracted from potato, rice, tapioca, sweet potato or corn, and the like, which is mainly composed of amylose having a linear structure and amylopectin having a molecular structure. It was preferred to add from 1 to 99% by weight.

The aliphatic polyester used in the present invention is a high molecular weight polymer having a melting point of 100 to 200 ° C and a weight average molecular weight of 100,000 to 200,000 having a high melt viscosity and melt strength, and includes 70 to 95 mol% of succinic acid residues and adipic acid residues. Esterification or transesterification of the acid component consisting of 5-30 mol%, 1,4-butanediol, and 0.01 to 1 mol% of a trifunctional or higher polyfunctional compound, and then, the product is introduced into a reactor equipped with a condenser and a stirrer. A heat stabilizer, a catalyst, and the like are added to obtain a condensation polymerization reaction at a pressure of 1 mmHg or less and a high temperature of 240 to 260 ° C.

Succinic acid and adipic acid are used as acid components, and succinic acid esters such as large methyl succinate, diethyl succinate, dipropyl succinate, dibutyl succinate, and dioctyl succinate instead of succinic acid. Compounds can be used.

Adipic acid functions to control the crystallinity of aliphatic polyester, and in particular, the use of 5 to 30 mol% of the acid component improves the moldability of the film. The molar ratio of the acid component consisting of succinic acid residues and adipic acid residues to 1,4-butanediol is reacted at a ratio of 1: 1 to 1: 2.

As the compound having trifunctional or higher polyfunctionality, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, tris (2-hydroxyethyl) -isocyanurate, trimellitic acid and trimellitic acid Anhydride, benzene tetracarboxylic acid, benzene tetracarboxylic anhydride, glycerin, etc. can be used.

These compounds are mixed in one kind or two or more kinds, and are added in a small amount in an aliphatic polyester copolymerization reaction at a ratio of 00.1 to 1 mol%, thereby rapidly increasing the molecular weight of the copolymer and consequently greatly improving the melt strength.

Aliphatic polyester is a high vacuum by esterification or transesterification of the above-mentioned three components, that is, the acid component, 1,4-butanediol and the polyfunctional compound, and then adding a thermal stabilizer and a catalyst in a reactor equipped with a condenser and a stirrer. It is obtained by condensation polymerization at high temperature.

The esterification or transesterification can be carried out at 220 ℃ or less to minimize the formation of by-products and pyrolysis, and the polycondensation reaction can have high melt viscosity and high melt strength when reacted at 240 ~ 260 ℃ with high vacuum below 1mmHg. An aliphatic polyester having

At this time, the polycondensation catalyst was used in the tin compound system or titanium compound system, it was added in the range of 0.01 ~ 0.1 mol% relative to the acid component. Examples of the tin compounds include tin oxides such as tin oxide and tin oxide, halogenated tin salts such as tin oxide, tin chloride, and sulfur yellow tin, monobutyl tin oxide, dibutyl tin oxide, monobutyl hydroxy tin oxide, Organic tin compounds such as dibutyltin dichloride, tetraphenyltin and tetrabutyltin. As the titanium compound, tetrabutyl titanate, tetramethyl titanate, tetraisopropyl titanate, tetra (2-ethylhexyl) titanate and the like are used. The heat stabilizer is used in an amount of 1.0 × 10 ⁻⁷ to 1.0 × 10 ⁻⁶ mol based on 1 g of the oligomer obtained by esterification or transesterification. Thermal stabilizers used include phosphoric acid, monomethyl phosphate, triphenyl phosphate, trimethyl phosphate, tributyl phosphate, trioctyl phosphate, monophenyl phosphate, triphenyl phosphate and derivatives thereof phosphorous acid, triphenyl phosphite, trimethyl phosphite and derivatives thereof iganox 1010, Iganox 1222, Igafos 168, Phenylphosphonic acid, etc. are used.

In the present invention, in order to improve the compatibility of starch and aliphatic polyester to obtain a good fluidity resin, by using an ethylene-vinyl alcohol copolymer having a hydrophilic group and a hydrophobic group as part of the synthetic resin to improve the hydrophilic properties of the starch mechanical properties and processability Was improved to enable molding into a film. In this case, the ethylene-vinyl alcohol copolymer is a high melting point compound having a total ethylene content of not more than 44%, and has a density of 1.14 g / cm 3, melting point of 164 to 188 ° C., vitrification transition temperature of 55 to 62 ° C., and melt index of 8 to 12 g / 10 min. Particularly preferred.

In the present invention, a plasticizer, a lubricant, and the like were added to improve processability when preparing a biodegradable resin, and as a plasticizer, mol, glycerine, ethylene diglycol, polyethylene glycol 1,4-butanediol, or the like was used alone or in a mixture. Triglycerol monostearate, triglycerol distearate, triglycerol tristearate was used alone or in combination.

The amount of water in the plasticizer was particularly effective to add 10 to 50% of starch and 0.5 to 10% by weight of lubricant based on the total composition.

Each component as described above is melt extruded by applying sufficient heat in a twin-screw extruder to adjust the moisture content of the final material exiting the die to 10-30% relative to the total composition. At this time, the barrel temperature is 60 ~ 220 ℃, screw RPM is 80 ~ 150, and torque is melt mixed under the conditions of 40 ~ 60 to produce a biodegradable resin.

The biodegradable resin prepared in this way can be molded in emerging molded articles, sheets, films and the like.

The following synthesis examples and examples further illustrate the present invention, but do not limit the scope of the present invention.

Synthesis Example 1

136 g (1.5092 mol) 1,4-butanediol, 123.38 g (0.9941 mol) succinic acid, 24.26 g (0.1660 mol) adipic acid, 0.4 g (0.0033 mol) trimethylol ethane and tetrabutyl 0.102 g (0.0003 mol) of titanate was added and It heated up to 120 degreeC over 40 minutes from normal temperature, and it heated up to 210 degreeC over 120 minutes, stirring. At this time, after completely flowing out the water of the side reaction product generated through the condenser, the pressure in the tube was gradually reduced to 0.5 mmHg over 45 minutes and the stirring reaction was performed for 10 minutes while the temperature of the tube was raised to 245 ° C. After stirring was stopped and nitrogen was introduced into the tube, the intermediate body was pressurized and discharged to obtain the desired aliphatic polyester copolymer.

The inherent viscosity of the produced decomposable resin was 1.72, and the melt strength determined at the extrusion temperature of 190 ° C. was 21.2.

Synthesis Example 2

136 g (1.5092 moles) of 1,4-butanediol, 102.74 g (0.8700 moles) of succinic acid, 42.38 g (0.2900 moles) of adipic acid, 0.4 g (0.0033 moles) of trimethylolethane and tetrabutyl in a reactor equipped with a stirrer and a condenser 0.102 g (0.0003 g) of titanate was added thereto, and the temperature in the reactor was raised to 120 ° C. over 40 minutes from room temperature, and the reaction was heated up to 210 ° C. over 120 minutes while stirring. At this time, after completely flowing out the water of the side reactions produced through the condenser, the pressure in the tube was gradually reduced to 0.5 mmHg over 45 minutes, and the stirring reaction was performed for 180 minutes while the temperature was raised to 245 ° C. After stirring was stopped and nitrogen was introduced into the tube, the polymer was pressurized and discharged to obtain the desired aliphatic polyester copolymer.

The inherent viscosity of the resin thus prepared was 1.75, and the extrusion strength was 28.4 at 190 ° C.

Example 1

40 parts by weight of corn starch, 64 parts by weight of the aliphatic polyester prepared in Synthesis Example 1, 55 parts by weight of synthetic resin with ethylene-vinyl alcohol (44% of ethylene molar content) 36 parts by weight of total resin, glycerin 4 parts by weight, 1 part by weight of triglycerol monostearate was mixed, and the moisture content was added to the starch at 10 to 40% to melt mixed extrusion in an extruder to prepare biodegradable pellets.

Screw Speed (RPM): 80

Torque: 40

Extruder Barrel Temperature: 110/150/180/190/180/160 ℃

EXAMPLES 2-6

The biodegradable resin pellets prepared in the same manner as in Example 1 were prepared as a blown film except that the amount of starch, the type and amount of the synthetic resin were changed as shown in Table 1, and the tensile strength was measured. Indicated.

The blown film is manufactured using HAAKE's RHEOCORD 90 blown film processing equipment with a diameter of 25 mm in the TURBULAR DIE, BLOW-UP RATIO = 4, TAKE-UP SPEED = 20m / MIN, SCREW SPEED = 9RPM, and barrel temperature It was set as 140/150/150/150 degreeC, and the film of thickness of 30-40 micrometers was obtained.

Claims (7)

Resin plasticizer is composed of 99 to 1% by weight of synthetic resin consisting of 90 to 20% by weight of ethylene-vinyl alcohol copolymer and 10 to 80% by weight of aliphatic polyester copolymer and 1 to 99% by weight of starch. A biodegradable resin composition characterized by melting and kneading after adding 10 to 50% and a lubricant to 0.5 to 10% by weight based on the total resin composition. The aliphatic polyester of claim 1, wherein the aliphatic polyester comprises an acid component residue consisting of 70 to 95 mol% of succinic acid residues and 5 to 30 mol% of adipic acid residues, a 1,4-butanediol residue, and a trifunctional or more than trifunctional polyfunctional compound residue. Biodegradable resin composition, characterized in that the intrinsic viscosity of 1.0 ~ 1 mol% or more. The biodegradable resin composition according to claim 2, wherein the compound having a trifunctional or higher polyfunctionality is mixed with one or two or more components of trimellitic acid, trimethylolpropane, trimethylolethane or glycerin. The biodegradable resin composition according to claim 1, wherein the ethylene-vinyl alcohol has an ethylene content of 1 to 44 mol%. The biodegradable resin composition according to claim 1, wherein water, glycerin, ethylene diglycol, polyethylene glycol, 1,4-butanediol, or the like is used alone or in combination as a resin plasticizer. The resin plasticizer according to claim 5, wherein 10 to 50% by weight of water is added to the starch, and glycerin, ethylene diglycol, polyethylene glycol, or 1,4-butanediol are mixed alone or in two or more components, and then the amount of 1 to 4 Biodegradable resin composition, characterized in that 5% by weight is added. The biodegradable resin composition according to claim 1, wherein the lubricant is added in an amount of 0.5 to 10% by weight based on the total composition, either alone or in combination with triglycerol monostearate, triglycerol distearate, and triglycerol tristearate. .